examples: tetris: add ubuntu dependencies list (#10456)

Author: wesinator

examples/tetris/README.md

@@ -1,2 +1,9 @@
 <img src='https://raw.githubusercontent.com/vlang/v/master/examples/tetris/screenshot.png' width=300>
 
+### Dependencies (Ubuntu)
+```sh
+sudo apt install libx11-dev
+sudo apt install libxi-dev
+sudo apt install libxcursor-dev
+sudo apt install libgl-dev
+```